Re: panic: softint screwup

[Nick Hudson <nick.hudson%gmx.co.uk@localhost>]

On 04/02/2020 23:17, Andrew Doran wrote:
> On Tue, Feb 04, 2020 at 07:03:28AM -0400, Jared McNeill wrote:
>
>> First time seeing this one.. an arm64 board sitting idle at the login prompt
>> rebooted itself with this panic. Unfortunately the default ddb.onpanic=0
>> strikes again and I can't get any more information than this:
>
> I added this recently to replace a vague KASSERT.  Thanks for grabbing the
> output.
>
>> [ 364.3342263] curcpu=0, spl=4 curspl=7
>> [ 364.3342263] onproc=0xffff00237f743080 => l_stat=7 l_flag=20000201 l_cpu=0
>> [ 364.3342263] curlwp=0xffff00237f71e580 => l_stat=1 l_flag=00000200 l_cpu=0
>> [ 364.3342263] pinned=0xffff00237f71e100 => l_stat=7 l_flag=00000200 l_cpu=0
>> [ 364.3342263] panic: softint screwup
>> [ 364.3342263] cpu0: Begin traceback...
>> [ 364.3342263] trace fp ffffffc101da7be0
>> [ 364.3342263] fp ffffffc101da7c00 vpanic() at ffffffc0004ad728 netbsd:vpanic+0x160
>> [ 364.3342263] fp ffffffc101da7c70 panic() at ffffffc0004ad81c netbsd:panic+0x44
>> [ 364.3342263] fp ffffffc101da7d40 softint_dispatch() at ffffffc00047bda4 netbsd:softint_dispatch+0x5c4
>> [ 364.3342263] fp ffffffc101d9fc30 cpu_switchto_softint() at ffffffc000085198 netbsd:cpu_switchto_softint+0x68
>> [ 364.3342263] fp ffffffc101d9fc80 splx() at ffffffc0000040d4 netbsd:splx+0xbc
>> [ 364.3342263] fp ffffffc101d9fcb0 callout_softclock() at ffffffc000489e04 netbsd:callout_softclock+0x36c
>> [ 364.3342263] fp ffffffc101d9fd40 softint_dispatch() at ffffffc00047b8dc netbsd:softint_dispatch+0xfc
>> [ 364.3342263] fp ffffffc101d3fcc0 cpu_switchto_softint() at ffffffc000085198 netbsd:cpu_switchto_softint+0x68
>> [ 364.3342263] fp ffffffc101d3fdf8 cpu_idle() at ffffffc000086128 netbsd:cpu_idle+0x58
>> [ 364.3342263] fp ffffffc101d3fe40 idle_loop() at ffffffc0004546a4 netbsd:idle_loop+0x174
>
> Something has cleared the LW_RUNNING flag on softclk/0 between where it is
> set (unlocked) at line 884 of kern_softint.c and callout_softclock().

Isn't it the case that softclk/0 is the victim/interrupted LWP for a soft{serial,net,bio}.
That's certainly how I read the FP values.

the callout handler blocked and softclk/0 became a victim as well maybe?

http://src.illumos.org/source/xref/netbsd-src/sys/kern/kern_synch.c#687

a soft{serial,net,bio} happends before curlwp is changed away from the blocking softint thread


Nick